3471 


iEx  ICtbrts 


SEYMOUR  DURST 


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3471 

Reprints  Vol,  I 


1.  The  Geology  of  Long  Island  1886 

2.  On  The  Met  amorphic  Strata  of  Southeastern 

New  York  1890 

3.  The  Geology  of  the  Crystalline  flocks  of 

Southeastern  New  York  1896 


Digitized  by  the  Internet  Archive 
in  2014 


http://archive.org/details/ongeologyoflongiOOmerr 


TH 


Geology  of  Long  Island, 


BY 


F.  J.  H.  MERRILL, 


[From  the  Annals  of  the  New  York  Academy  of 
Sciences,  Vol.  Ill,  Nos.  11  &  12,  1886.] 


Geology  of  Long  Island. 


341 


XX. —  On  the  Geology  of  Long  Inland. 

BY  F.   J.    H.  MERRILL. 
Read  November  7,  1884. 

The  following  contributions  to  the  Geology  of  Long  Island  are 
the  result  of  some  five  weeks'  exploration  and  study  of  that  well- 
known  and  interesting  region,  during  the  summer  of  1883.  This 
paper  is  but  preliminary  ;  and  many  questions  which  have  been 
merely  touched  upon  or  wholly  neglected,  the  writer  hopes  to 
discuss  at  length  when  more  extended  research  and  deeper  exca- 
vations have  given  him  further  data. 

The  surface  geology  of  this  region  has  already  been  minutely 
described  by  Mather  in  his  Report  on  the  Geology  of  the  First 
District  of  New  York,  1843,  and  also,  with  special  reference  to 
the  glacial  deposits,  by  Mr.  Warren  Upham,  in  his  articles  on 
"  Terminal  Moraines  of  the  North  American  Ice  Sheet,"  Am. 
Jour.  Sci.,  Ill,  18.  I  shall  therefore  review  very  briefly  the 
physical  characteristics  of  the  island  and  endeavor  to  throw  what 
additional  light  I  can  upon  its  geological  history,  from  the  study 
of  sections  of  strata  recently  exposed,  and  such  other  phenomena 
as  it  has  been  my  fortune  to  observe. 

Long  Island  as  a  whole  is  comparatively  low  and  flat,  but 
throughout  the  central  part  is  a  range  of  hills  extending  from 
Bay  Ridge  northeasterly  to  Roslyn,  and  thence  continuing  to 
Montauk  Point  in  a  series  of  elevations,  the  more  important  of 
which  are  known  as  West,  Dix,  Comae,  Bald,  and  Shinnecock 
Hills.  The  average  height  of  this  chain  is  about  250  feet ;  but 
at  some  points  it  is  much  greater.  Harbor  Hill  at  Roslyn  is  384 
feet  above  tide  ;  Jane's  Hill  is  383  feet  high  ;  Reuland's  Hill  has 
an  elevation  of  340  feet,  and  Wheatly  Hill  is  369  feet  above  the 
sea. 

There  is  also,  along-  the  north  shore,  an  elevation  which  usually 
follows  the  contour  of  the  numerous  deep  bays  and  inlets,  vary- 
ing in  bight  from  30  to  2C0  feet,  and  almost  continuous  from 


342 


Geology  of  Long  Island. 


Astoria  to  Orient  Point.  These  two  ranges  of  hills  are  the  re- 
sult of  glacial  action,  and  the  more  southern  chain  marks  the 
southern  limit  of  the  drift. 

Upham  and  others,  in  speaking  of  these  ranges,  have  called 
them  moraines.  If  the  word  moraine  is  to  be  thus  used,  and 
present  custom  in  the  United  States  appears  to  sanction  the  use, 
it  must  be  taken  in  a  different  sense  from  that  accorded  to  it  in 
most  regions  of  glacial  action.  In  Switzerland  and  other  moun- 
tainous countries,  the  term  is  applied  to  great  accumulations  of 
boulders  and  rock  detritus,  piled  up  along  the  sides  or  front  of 
a  glacier.  Throughout  most  of  Long  Island  and  at  many  points 
on  the  New  England  coast,  however,  the  thickness  of  the  drift 
on  the  ridges  marking  the  southern  limit  of  glacial  extension  is 
very  slight  and  in  some  cases  it  is  wanting.  In  these  cases,  the 
term  moraine  would  be  synonymous  with  the  southern  limit  of 
the  continental  glacier. 

South  of  the  backbone,  as  the  central  range  of  hills  is  called, 
the  surface  is  nearly  level,  gently  sloping  southward  in  an  unbro- 
ken gravelly  plain  ;  while  between  this  ridge  and  the  north  shore 
is  a  second  plain  with  an  elevation  of  50  to  100  feet,  and  espe- 
cially noticeable  between  Port  Jefferson  and  Eiverhead.  From 
many  of  the  deep  bays  on  the  north  shore,  valleys  extend  through 
the  hills  in  a  southerly  direction.  These  depressions,  thirty  in 
number  between  East  New  York  and  Eiverhead,  have  been  ex- 
plored by  Mr.  Elias  Lewis,  Jr.,  of  the  Long  Island  Historical 
Society.*  He  finds  them  to  average  about  25  feet  in  depth  and 
to  be  occupied  usually  by  small  streams  most  of  wdiich  flow  south- 
ward. These  valleys  are  evidently  the  beds  of  rivers  formed  by 
the  melting  of  the  ice  sheet  in  the  Champlain  Period. 

There  are  no  important  lakes  or  rivers  now  on  Long  Island, 
but  there  are  numerous  ponds  of  clear  cool  water,  without  visi- 
ble inlet  or  outlet.  The  existence  of  these  ponds  depends  on  the 
fact  that  in  the  stratified  sands  of  the  island,  which  are  under- 
lain by  clays,  a  uniform  water-level,  or  plain,  exists,!  which 
rises  northward  from  low-tide-level  on  the  south  shore  at  the 
rate  of  121  feet  per  mile.    Wherever  a  basin  has  been  excavated 


*  Am.  Jour.  Sci.,  Scries  III,  Vol.  XIII. 
f  Dana,  Manual  of  Geology,  p.  664. 


Geology  of  Long  Island. 


343 


below  the  surface  of  this  plain,  it  would  necessarily  be  filled  by 
these  subterranean  waters,  which,  by  their  constant  percolation 
through  the  sand,  would  remain  pure  and  clear,  without  material 
or  sudden  change  of  level  under  average  conditions.  The  largest 
of  these  ponds  is  Lake  Ronkonkoma,  which  is  three  miles  in  cir- 
cumference, and  has  a  maximum  depth  of  83  feet. 

The  coast-line  of  Long  Island  is  strikingly  irregular.  Along 
the  north  shore  are  eight  deep  and  extensive  bays,  which  form 
excellent  harbors,  and  also  a  large  number  of  inlets,  most  of 
which  are  navigable.  At  the  heads  of  these  bays,  numerous 
springs  of  pure  water  issue  from  the  hillsides,  indicating  the 
presence  of  an  impervious  stratum  within  the  hills.  The  east 
end  of  the  island  is  penetrated  by  Great  and  Little  Peconic  Bays 
to  a  depth  of  22  miles,  while  the  south  shore  west  of  Southhamp- 
ton for  about  95  miles,  consists  of  an  intricate  series  of  shallow 
creeks  partly  surrounded  by  salt  marsh,  tributary  to  Shinnecock, 
Moritches,  Great  South,  Hempstead,  and  other  bays,  which  are 
divided  from  the  ocean  by  long  sand  beaches,  or  reefs  intersected 
in  places  by  narrow  inlets.  Shelter,  Eobbin's,  Plum,  Gull  and 
Gardiner's  Islands,  which  form  part  of  Suffolk  County,  New 
York,  do  not  differ  from  Long  Island  essentially  in  physical  or 
ge ol  og  i  c al  c h  ar ac  t  e  r i  s  t i  c s . 

The  lithology  of  the  island  is  comparati vely  simple,  the  crys- 
talline rocks  being  confined  to  quite  a  limited  area.  The  greater 
part  of  the  region  consists  of  gravel,  sand  and  clay,  overlain 
along  the  north  shore  and  for  some  distance  southward,  by  gla- 
cial drift.  This  material  forms  an  important  element  of  the 
surface  formation,  and  though  it  has  been  already  described  by 
Mather  and  Upham,  I  shall  devote  a  short  space  to  its  discussion. 
For  the  sake  of  clearness,  we  may  describe  the  drift  as  of  two 
kinds  :  1st,  the  till  or  drift  proper,  a  heterogeneous  mixture 
of  gravel,  sand  and  clay,  with  boulders,  and  2d,  the  gravel 
drift,  a  deposit  of  coarse  yellow  gravel  and  sand,  brought  to  its 
present  place  by  glacial  and  alluvial  action,  but  existing  near 
by  in  a  stratified  condition,  before  the  arrival  of  the  glacier. 
This  yellow  gravel  drift,  which  in  a  comparatively  unaltered 
condition  forms  the  soil  of  the  pine  barrens  of  southern  and 
eastern  Long  Island,  and  is  exposed  in  section  at  Grossman's 
brickyard  in  Huntington,  is  equivalent  to  and  indeed  identical 


Geology  of  Long  Island. 


wiili  the  yellow  drift  or preglaeial  drift  of  New  Jersey,  a  forma- 
tion of  very  great  extent  in  that  State,  and  of  which  the  origin 
and  source  have  not  yet  been  fully  explained,  though  it  is  always 
overlain  by  the  glacial  drift  proper  where  these  formations  occur 
together. 

In  the  hills  near  Brooklyn  the  till  attains  its  maximum  depth. 
This  has  never  been  definitely  ascertained,  but  is  probably  be- 
tween 150  and  200  feet.    The  only  information  we  have  on  the 
subject  is  from  a  boring  in  Calvary  Cemetery,  where  the  drift 
was  139  feet  deep,  and  this  point  is  nearly  five  miles  north  of 
Mt.  Prospect,  which  is  194  feet  high  and  probably  consists  for 
the  most  part  of  till.    The  occurrence  of  this  till  is  quite  local 
and  very  limited  along  the  north  shore  between  Roslyn  and  Hor- 
ton's  Point.    From  the  former  locality  eastward  the  hills  are 
mainly  composed  of  stratified  gravel  and  sand,  probably  under- 
lain by  clay.    On  the  railroad  between  Syosset  and  Setauket.  is 
an  abundance  of  coarse  gravel  with  but  slight  stratification. 
East  of  Setauket  for  some  distance  the  drift  is  a  fine  yellowish 
sand  which  washes  white  on  the  surface,  and  at  Wading  River 
the  drift  with  cobble-stones  was  only  eighteen  inches  thick  where 
exposed,  being  underlaid  with  fine  yellow,  sand.    Along  the  re- 
mainder of  the  north  shore  to  Orient  Point,  G  feet  was  the  max- 
imum depth  of  drift  observed.    Under  this  were  stratified  sands, 
gravels  and  clays,  usually  dipping  slightly  from  the  shore.  On 
Brown's  Hills,  north  of  Orient,  the  drift  is  overlaid  by  3  feet  of 
fine  micaceous  sand,  which  has  probably  been  carried  to  its  pres- 
ent position  by  the  wind.    The  drift  at  this  locality  is  a  clayey 
till,  and  its  surface  is  strewn  with  an  abundance  of  boulders  of 
coarse  red  gneiss.    On  Shelter  Island  are  high  ridges  of  gravel 
overlain  by  a  few  feet  of  till.    The  hills  from  Sag  Harbor  east- 
ward are  also  composed  partially  of  unmodified  drift,  but  the 
most  extensive  deposit  on  the  east  end  of  Long  Island  is  between 
Nepeague  Bay  and  Montauk  Point.    Here  the  drift  is  disposed 
in  rounded  hillocks  from  80  to  200  feet  above  the  sea,  with  bowl 
and  trough-shaped  depressions  between.    The  bluffs  along  the 
south  shore,  which  are  rapidly  yielding  to  the  action  of  the  waves, 
consist  for  the  most  part  of  boulder  clay  and  hard-pan  of  consid- 
able  depth,  covered  by  a  shallow  layer  of  till.    At  a  few  places, 
however,  on  the  south  shore,  west  of  the  point,  laminated  blue 


Geology  of  Long  Island. 


345 


clay  streaked  with  limonite  occurs,  intercalated  with  the  till. 
At  the  end  of  the  point,  a  similar  bed  of  clay  is  exposed,  over- 
lain by  stratified  sand.  From  the  extremely  limited  character 
of  the  exposures,  I  am  unable  to  determine  whether  the  clay  un- 
derlies the  whole  of  the  point  or  is  merely  local  in  its  occurrence. 
In  character  and  position,  however,  it  is  analogous  to  beds  occur- 
ring on  Block  Island. 

The  boulders  of  Long  Island  attract  the  attention  of  the  geol- 
ogist by  their  size  and  variety.  They  represent  almost  every 
geological  age  ;  fossiliferous  rocks  of  the  Helderberg,  Oriskany 
and  Cauda  Galli,  Hamilton,  Chemung  and  Eocene  periods  having 
been  found  in  the  drift.  Examples  of  these  are  in  the  collection 
of  the  Long  Island  Historical  Society.  There  are  also  various 
members  of  the  Archaean  series,  viz.,  gneiss,  granite,  syenite, 
hornblende,  chlorite,  talcose  and  mica  schist,  limestone,  dolo- 
mite, and  serpentine  :  and  the  Palaeozoic  and  Mesozoic  ages  are 
represented  by  Potsdam  sandstone,  Hudson  River  slate,  Oneida 
conglomerate  or  Shawangunk  grit,  Catskill  sandstone,  and  Tri- 
assic  sandstone  and  trap.  As  the  lithology  of  the  boulders  has 
been  described  in  detail  by  Mather,*  it  would  be  superfluous  for 
me  to  undertake  a  similar  description. 

In  addition  to  the  rocks  mentioned  above,  ^  ferruginous  sand- 
stone and  conglomerate  occur  abundantly  in  fragments  along  the 
east  shore  of  Hempstead  Harbor,  and  in  the  drift  between  Glen 
Cove  and  Oyster  Bay.  Many  of  these  fragments  contain  vegeta- 
ble impressions,  but  in  only  two  localities  have  any  leaf  prints 
been  found.  These  were  West  Island,  Dosoris,  and  the  well  of 
the  Williamsburg  Gas  Co.  The  prints  are  supposed  to  belong 
to  Cretaceous  plants,  but  the  evidence  is  incomplete. 

Many  of  the  erratic  blocks  are  of  immense  size,  one  in  particu- 
lar, of  gneiss,  on  Shelter  Island,  near  Jennings'  Point,  con- 
tained as  a  solid  mass  over  9000  cubic  feet.  It  has  split  in  three 
pieces  since  it  was  deposited.  Matheif  mentions  a  mass  of  gra- 
nite near  Plandome,  which  was  estimated  to  contain  8000  cubic 
yards  above 'the  surface  of  the  ground. 

Having  thus  briefly  reviewed  the  characters  of  the  surface 


*  Geol.  1st  Dist.  X.  Y.,  pp.  16.5-177. 
f  Geol.  1st  Dist.,  p.  174. 


Geology  of  Long  1  si  and. 


drift,  we  will  now  consider  in  detail  the  strata  which  underlie  it. 
The  crystalline  rocks  outcrop  along  the  shore  at  Hellgate  and 
over  a  limited  area  in  the  vicinity  of  Astoria.  They  consist  of 
finely  laminated  gneiss  and  schists,  tilted  at  a  high  angle,  and 
belong  to  the  same  formation  as  the  rocks  of  Manhattan 
Island.  I  am  informed  by  Mr.  Elias  Lewis,  Jr.,  that  in 
boring  an  artesian  well  in  Calvary  Cemetery,  near  Brooklyn,  a 
bed  of  gneiss  was  encountered  at  a  depth  of  182  feet.  Farther 
than  this,  we  know  nothing  of  the  extent  of  the  crystalline  rocks 
on  Long  Island.  The  section  obtained  in  the  boring  mentioned 
was  as  follows  : 

Surface  loam  and  drift,     -       -       -  139  feet. 

Greenish  earth,   39  " 

AVhite  clay  with  red  streaks,     -       -  4  " 

Gneiss,   400  " 


Total,       -       -        582  feet. 

The  greenish  earth  referred  to,  lost  its  color  on  being  treated 
with  hydrochloric  acid,  and  the  white  residue  examined  under 
the  microscope  appeared  to  consist  of  minute  fragments  of  kao- 
linized  feldspar,  with  occasional  grains  of  quartz  sand.  The 
acid  solution  gave  a  strong  reaction  for  iron,  indicating  a  proba- 
ble admixture  of  glauconite  with  the  material.  It  is  stated  in 
Cozzens'  Geol.  Hist,  of  N.  Y.  Island,  that  a  shell  of  Exogyra 
costata,  with  green-sand  adhering,  was  found  between  Brooklyn 
and  Flatlands,  at  a  depth  of  60  feet.  This  locality  is  about  live 
miles  south  of  the  well  just  mentioned,  and  would  indicate  the 
presence  of  Cretaceous  strata  near  Brooklyn. 

The  following  data,  also  furnished  by  Mr.  Lewis,  of  a  well  dug 
by  the  Nassau  Gas  Light  Co.,  in  Williamsburg,  will  give  an  idea 
of  the  formation  at  that  locality  : 

Surface  loam,  3  feet. 

Quick-sand  (so  called),       -  2  " 

Boulder  clay,  somewhat  sandy,       -    7<)  " 

Blue  clay  with  pebbles.       -  -       27    ' 4 


Ovster  shells,        ....  6  inches. 


Total,       -        102  feet  0  inches. 


Geology  of  Long  Island. 


347 


The  shell-bed  was  underlain  by  quicksand  bearing  water. 

In  the  vicinity  of  Manhasset,  on  the  road  to  Port  Washington, 
are  extensive  exposures  of  stratified  sand,  more  or  less  inclined 
from  the  horizontal.  About  200  yards  south  of  the  post  office, 
on  the  west  side  of  the  road,  is  a  bank  about  40  feet  high,  com- 
posed of  a  white,  coarse,  laminited  sand,  streaked  with  hydrous 
peroxide  of  iron,  the  layers  dipping  S.  E.  13°.  A  little  north- 
east of  the  post  office,  along  the  road,  there  are  banks  of  red 
sand  cemented  together  in  places  by  sesquioxide  of  iron  and  re- 
sembling the  Cretaceous  red  sand  bed  of  New  Jersey. 

On  the  shore  of  Manhasset  Bay,  near  Port  Washington,  are 
high  banks  of  coarse  yellow  stratified  sand  and  gravel.  This  de- 
posit is  very  irregular  in  its  stratification,  as  it  shows  in  many 
places  the  "flow  and  plunge"  structure  described  by  Dana,  and 
which  is  evidently  produced  by  swift  currents.  The  depth  of 
this  formation  cannot  be  determined,  it  is  probably  not  less  than 
150  feet,  and  possibly  is  much  greater.  These  beds  dip  about 
15°  W.  ;  the  strike  is  nearly  due  north  and  south.  Along  the 
shore  of  Manhasset  Bay,  from  Port  Washington  to  Barker's 
Point,  are  extensive  banks  of  stratified  sand  and  gravel,  much 
stained  with  iron  and  dipping  westward.  At  Prospect  Point 
and  Mott's  Point,  the  banks  are  composed  of  coarse  gravel  simi- 
lar to  that  at  Port  Washington. 

Between  Roslyn  and  Glen  Cove,  there  are  high  banks  of  red  and 
flesh-colored  sands,  while  at  Carpenter's  clay  pits  a  most  interest- 
ing section  is  presented  (fig.  1).  The  greatest  hight  of  this  sec- 
tion is  73  feet,  the  strike  of  the  beds  being  X.  80°  W.  and  the 
dip  about  37°  northerly.  The  layers  here  are  composed  of  coarse 
white  gravel  and  sand,  apparently  consisting  of  quartz,  but  sus- 
ceptible of  being  easily  crushed  in  the  hand.  The  pebbles  are 
traversed  by  innumerable  cracks,  and  appear  to  have  been  sub- 
jected to  the  action  of  an  alkaline  solution.  Interstratified  with 
the  gravel  are  layers  of  fine  white  clay,  from  six  inches  to  one  foot 
in  thickness,  stained  pink  in  some  places,  and  containing  occasion- 
al fragments  of  a  soft  hematite  or  red  ochre.  Besides  these  beds, 
there  is  a  deposit  of  kaolin  farther  south,  but  its  stratigraphical 
relations  to  the  layer  exposed  could  not  be  determined.  This  kao- 
lin is  a  soft  white  granular  clayey  substance,  consisting  chiefly  of 
hydrous  silicate  of  alumina  from  the  decomposition  of  feldspar. 


Geology  of  Long  Island. 


In  fad  the  whole  deposit  would  seem  to  be  the  decomposition 
product  of  a  granulite  rock  such  as  occurs  abundantly  in  West* 
Chester  Co.,  X.  Y.,  and  in  southwestern  Connecticut.  Lu  the  north 
end  of  the  bank  is  an  un  conform  ability,  the  gravel  beds,  which 
dip  37°,  being  overlaid  by  stratified  sand  dipping  15°  in  the  same 
direction.  The  layers  shown  in  this  section  form  che  north  slope 
of  an  anticlinal  flexure,  the  lowest  beds  being,  I  am  informed 
by  Mr.  Coles  Carpenter,  one  of  the  proprietors,  almost  vertical. 
An  excavation  made  about  100  yards  W.  S.  W.  of  the  main  pit, 
for  the  purpose  of  obtaining  some  leaf-prints,  exposed  the  fol- 
lowing section  : 

Gravelly  drift,       ...      6  feet. 

White  sand,       -  18  inches. 

Coarse  "  6  " 

Reddish  clay,     -       -       -       -  2  " 

(J i  ey  sandy  carbonaceous  clay 
with  leaf-prints,       -       -       4  " 

14  feet. 

These  beds  dipped  about  15°  S.  W.,  the  locality  being  on  the 
south  slope  of  the  anticlinal.  Owing  to  the  sandy  nature  of  the 
clay,  and  the  dryness  of  the  season,  no  satisfactory  specimens 
could  be  obtained.  The  prints  retain  no  carbon,  but  simply 
show  the  venation  of  the  leaves. 

North  of  Sea  Cliff,  along  the  shore  of  Hempstead  Harbor,  to 
the  Glen  Cove  steamboat  landing,  is  a  series  of  clay  beds  out- 
cropping on  the  beach  and  dipping  N.  by  E.  about  10°  ;  these 
beds  are  of  various  colors,  blue,  yellow,  reddish,  white  and  black. 
The  reddish  clays  contain  fragments  of  a  soft  hematite,  and  one 
of  the  blue  layers  is  overlaid  by  about  two  inches  of  lignite  in 
small  fragments.  Other  layers  contain  pyritized  lignite  and 
nodular  pyrites,  but  it  is  impossible  to  determine  the  nature  and 
order  of  these  beds  accurately,  without  extensive  excavations. 
Dark  clays,  with  pyrites,  are  also  reported  to  occur  in  Carpenter's 
pits  at  a  considerable  depth.  In  the  beds  of  decomposed  gravel 
already  mentioned,  are  many  geodes  of  sand  cemented  together 
by  hydrous  and  anhydrous  sesquioxide  of  iron,  containing  a 
dark  granular  mass  which  analysis  shows  to  consist  chiefly  of 
decomposed  pyrites.  The  conclusion  is  therefore  justifiable  that 
the  nodules  of  marcasite  which  once  existed  in  the  gravel  beds 


Geology  of  Long  Island. 


349 


have  decomposed  by  oxidation,  and  the  resulting  ferric  oxide  , 
has  cemented  the  sand  about  them  into  a  hard  crust,  while  the 
nodules  in  the  clay  beds  which  were  protected  from  oxidation 
have  remained  unaltered. 

North  of  Glen  Cove,  clays  of  various  kinds  occur  at  East  and 
West  Islands,  Dosoris',  and  at  Matinnecock  Village.  At  the 
East  Williston  brickyard,  near  Mineola,  there  is  a  local  deposit 
of  grey  micaceous  clay.  The  depth  of  this,  where  excavated, 
varies  from  7  to  18  feet.  The  clay  overlies  white  laminated 
sands,  stained  with  limonite,  the  upper  surface  of  the  sand  being 
cemented  together  for  the  depth  of  an  inch  by  the  yellow  oxide. 
Over  the  clay  is  about  six  inches  of  black  alluvial  earth. 

At  the  brick-yard  on  Centre  Island,  in  Oyster  Bay,  there  is  a 
deposit  of  brown  sandy  clay  over  a  bed  of  more  homogeneous  and 
tougher  clay.  These  beds  undulate  in  an  east  and  west  direction 
or  away  from  the  shore,  and  the  lower  stratum  contains  shaly 
concretions  or  claystones.  About  a  mile  north  of  the  brick-yard, 
it  is  said  that  a  bed  of  white  fire  clay  has  been  found  at  a  depth 
of  25  feet  under  the  drift  and  sand.  A  little  west  from  the  U. 
S.  Fish  Hatchery,  at  the  head  of  Cold  Spring  Harbor,  is  a  bank 
of  stratified  gravel  70  feet  high.  About  40  feet  below  the  top 
of  this  bank  is  an  exposure  of  laminated  sand  and  sandy  clay 
stained  red,  brown  and  yellow  with  oxide  of  iron,  and  a  short 
distance  below,  a  chalybeate  spring  issues  from  the  bank.  The 
clay  deposit  at  Stewart's  brick-yard,  at  Bethpage,  is  about  60 
feet  in  depth.  The  surface  stratum  is  a  yellowish  micaceous 
clay,  the  lower  part  being  mottled  blue  and  yellow.  It  probably 
was  originally  a  gray  or  blue  clay,  its  present  yellow  color  being 
due  to  the  peroxidation  and  hydration  of  the  iron  contained. 
Of  this  stratum  there  is  about  35  feet  ;  below  is  about  five  feet 
of  reddish  sandy  clay,  and  beneath  this  a  blue-black  sandy  clay 
containing  nodules  of  white  pyrites.  This  stratum  is  about  25 
feet  deep  and  is  underlaid  by  white  sand.  The  beds  are  some- 
what disturbed  and  folded,  the  uppermost  being  slightly  undu- 
lating, while  the  two  lower  appear  to  be  raised  in  a  fold  trending 
nearly  E.  and  W. 

I  am  indebted  to  Mr.  Lewis  for  the  following  section  obtained 
in  digging  a  well  at  Jericho  in  1878,  on  the  premises  of  Mr.  Jules 
Kunz  : 


350 


Geology  of  Long  Island. 


Surface  loam,       ....  15  ft. 

Drift,   36  ' ' 

Yellow  gravel,      -       -       -       -  81  " 

Sand,   15  " 

Sandy  clay  with  a  carbonized  branch,  4  " 

Yellow  clay,   3  " 

Blue  and  gray  sandy  clay  with  pyrites,  30  " 

Micaceous  sand,        -       -       -       -  14  "  G  in. 

Total,       -       -      198  ft.  6  in. 

From  the  same  authority  I  have  the  following  section  of  a  well 
on  Barnum's  Island  : 

Sand  and  gravel,  stratified,        -       -    ?0  ft. 
Clay  and  clayey  sand  with  lignite,  -       56  " 
Gravel  and  fine  sand  with  clayey  sand,    44  " 
Blue  clay,  clayey  sand  and  silt,  with  lig- 
nite and  pyrites,       -       -       -     168  *' 

Total,       -       -        338  ft. 

In  the  third  stratum,  at  a  depth  of  168  feet,  a  fragment  of  the 
stem  of  a  crinoid  was  found  which,  together  with  a  complete  set 
of  specimens  from  the  well,  is  in  the  collection  of  the  Long  Island 
Historical  Society.  The  fossil  fragment  is  probably  from  some 
Palaeozoic  formation,  and  has  no  special  importance. 

At  Crossman's  brick-yard  in  Huntington,  on  the  east  shore  of 
Cold  Spring  Harbor,  we  have  the  section  shown  in  Fig.  2  of  plate 
XXVII.  The  ridge  which  is  intersected  here  trends  a  little  E. 
of  N.    The  section  is  as  follows  : 


Till  and  stratified  drift,  ...  10  ft. 

Quartz  gravel,   45  " 

Red  and  blue  "loam"  or  sandy  clay,  20  " 

Diatomaceous  earth,       -       -       -  3  " 

YTellow  and  red  stratified  sand,  -       -  20  " 

Red  plastic  clay,     -       -       -       -  20  " 

Brown    "     "   25  " 


Total,  - 


143  ft. 


Geology  of  Long  Island. 


351 


The  bed  of  diatomaceous  earth  is  of  undetermined  extent,  and 
appears  to  be  replaced  a  little  to  the  east  by  a  blue  clay,  which 
however  contains  some  diatoms.  It  is  undoubtedly  equivalent 
to  the  bed  of  ochre  which  overlies  the  sand  throughout  the  re- 
mainder of  the  section.  At  Jones's  brick-yard,  adjoining  Cross- 
man's,  there  is  a  similar  fold  nearly  at  right  angles  to  the  first, 
but  the  upper  portion  has  been  removed  by  ice  or  water  down  to 
the  sand.  This  stratum,  which  is  yellow  and  brown  in  the  north 
part  of  Crossman's  yard,  is  dark  red  in  the  south  end  *and  at 
Jones's.  It  appears  to  be  mixed  with  a  fine  red  clayey  matter 
which  separates  on  washing. 

The  formation  on  Lloyd's  Neck  is  similar  to  that  at  Cross- 
man's,  with  regard  to  the  composition  of  the  strata.  On  the 
north  side  of  East  Neck,  at  Eckerson's  brick-yard,  is  a  deposit 
of  reddish  clay  underlain  by  brown  clay  very  similar  to  that  at 
Crossman's.  To  the  west  of  this  is  a  bank  of  white  quartz  gravel, 
while  on  the  east  is  an  extensive  deposit  of  fine  white  quartz 
sand,  laminated  with  red,  yellow  and  brown  waved  streaks. 
The  exact  relations  of  these  strata  I  was  unable  to  determine, 
but  from  their  analogies  to  other  deposits  I  am  inclined  to  con- 
sider the. laminated  sand  as  the  more  recent, 

On  the  north  end  of  Little  Neck  there  is  another  large  deposit 
of  these  laminated  sands.  At  this  point  they  dip  S.E.  about 
15°.  The  following  section  given  in  Mather's  Report  Geol.  of 
1st  Dist.,  p.  254,  is  more  complete  than  any  I  could  obtain  at 
the  time  of  my  visit : 


1. 

Loose  surface  sand,  ------ 

n 

ft. 

2. 

Dark  colored  loamy  sand  and  clay, 

3 

3. 

Yellowish  and  reddish  sand,  waved  lamina?, 

H 

(( 

4. 

White  sand  tinged  with  yellow, 

4 

it 

5. 

Sand  similar  but  ditfering  in  color  and  direction 

of  laminae,  

4 

a 

6. 

Sand  red,  waved  laminae,  - 

30 

(( 

7. 

White  clay,  

4 

i  i 

8. 

White  sand  tinged  with  red  or  yellow, 

4 

(( 

9. 

Clay,  white  like  No.  7,  

3 

i  ( 

10.  Sand,  white  like  No.  8,  

3 

(( 

Geology  of  Long  Island. 


11.  White  clay  like  No.  7,  5  ft. 

12.  White  sand  like  No.  8,  5  " 

Total,  70  ft. 

South  of  this  deposit,  about  half  a  mile,  is  a  clay-pit  which  is 
worked  by  Capt.  Sammis,  of  Northport.  Here  the  stratification 
is  as  follows : 

Surface  loam  and  drift,       -       -       -    3  or  4  ft. 

Sandy  kaolin,   10  " 

Yellowish  clay,  4  " 

Dark  blue  sandy  clay,    -       -       -       -       15  " 
Dip,  5°  W. 

The  lowest  stratum  is  separated  into  thin  laminae  by  equally 
thin  layers  of  sand,  in  which  are  numerous  impressions  of  frag- 
ments of  vegetable  matter,  but  only  one  leaf-print  has  been 
found  ;  this  is  in  the  museum  of  the  Long  Island  Historical  So- 
ciety. It  is  a  small,  broadly  elliptical  leaf,  about  f  in.  long.  In 
this  same  bed  was  found  several  years  ago  a  shark's  tooth  which 
has  been  identified  as  Carcharodon  angustidens  or  megalodon. 
It  is  difficult  to  determine  the  relation  of  this  stratum  to  the 
other  layers  in  the  vicinity,  but  it  is  probably  of  the  same  period 
as  the  laminated  sands,  and  seems  to  be  identical  with  a  bed 
which  Mather  describes  as  occurring  on  Eaton's  Neck.  (Geol. 
1st  Dist.,  p.  228.) 

At  the  brick-yard  near  West  Deer  Park,  beneath  the  gravel 
and  drift,  is  a  stratum  of  flesh-colored  clay,  underlaid  by  dark 
blue  clay  containing  pyrites.  I  was  informed  by  the  owner,  Mr. 
Conklin,  that  in  the  centre  of  the  hill  of  gravel  the  clay  rises  up 
in  a  fold.  Between  Bethpage  and  West  Deer  Park  is  a  deposit 
of  ferruginous  conglomerate  and  sandstone  formed  by  the  solidi- 
fication of  the  stratified  gravel  and  sand  or  yellow  drift.  This 
rock  is  very  similar  in  composition  and  appearance  to  one  which 
occurs  in  fragments  in  the  glacial  drift  and  contains  vegetable 
impressions.  At  Provost's  yard,  near  Fresh  Ponds,  are  quite  ex- 
tensive beds  of  brown  sandy  clay,  reddish  clay,  and  chocolate- 
brown  clay,  dipping  from  the  shore.    The  red  and  chocolate 


Geology  of  Long  Island. 


353 


clays  are  probably  identical  with  the  similar  beds  at  Grossman's 
in  Huntington. 

Lake  Ronkonkoma  is  in  a  basin  of  which  the  bottom  is  about 
210  feet  below  the  high  ground  on  the  south.  Its  southern  bank 
is  composed  of  laminated  sand  streaked  with  oxide  of  iron,  and 
the  rest  of  the  shore  appears  to  be  formed  of  the  same  material. 
At  Oiine  Keck  Point  are  bluffs,  60  feet  high,  of  sand  and  gravel 
containing  masses  of  ferruginous  sandstone  of  recent  date.  At 
Herod's  Point  the  bluffs  consist  of  fine  yellow  sand  and  gravel, 
slightly  stratified,  and  dipping  a  few  degrees  south.  Limonite 
concretions  are  here  abundant.  The  bluffs  at  Friar's  Head  are 
about  120  feet  high,  and  consist  of  yellow  stratified  sand  with 
pebbles.  Over  these  is  a  dune  of  yellowish  drifted  sand  90  feet 
high,  making  the  total  hight  of  the  peak  210  feet.  On  the  west 
side  of  Bobbin's  Island  is  an  exposure  of  blue  clay  overlaid  by 
laminated  ferruginous  sand.  The  depth  of  this  clay-bed  has  not 
been  determined,  but  it  is  similar  in  appearance  and  quality  to 
some  of  the  clays  near  Huntington,  especially  at  Grossman's 
brick-yard.  A  chalybeate  spring  issues  from  the  laminated  sand 
on  the  shore,  a  little  to  the  south  of  the  clay-pit.  The  clay  bed 
appears  to  dip  southward  about  10°  throughout  the  whole  extent 
of  the  island.  Near  the  railroad  between  Southold  and  Green- 
port  are  two  brick-yards.  At  the  more  easterly  of  the  two  there 
are  various  deposits  of  stratified  sand  and  clay  very  much  folded 
and  tilted.  At  this  place  the  section  exposed  shows  two  parallel 
folds,  the  axes  of  which  trend  a  little  N.  of  E.  The  upper  stra- 
tum of  brown  clay  contains  angular  fragments  of  mica  schist. 
(See  fig.  3.)  At  the  other  yard  they  are  working  a  bed  pre- 
cisely similar  to  that  just  mentioned  and  also  containing  angular 
fragments  of  rock. 

On  Shelter  Island  are  high  hills  of  gravel  with  a  thin  covering 
of  till  ;  the  highest  point  is  about  180  feet  above  tide.  West  of 
the  village  of  Orient  is  a  narrow  isthmus  of  sand  beach  and  salt 
meadow,  about  a  mile  and  a  half  long  and  not  more  than  ten 
feet  above  tide.  East  of  this,  on  the  north  side  of  the  peninsula, 
Brown's  Hills  extend  along  the  shore  for  a  mile  and  a  half,  the 
highest  point  being  128  feet  above  Long  Island  Sound.  The 
structure  of  these  hills  is  difficult  to  determine,  as  extensive  land 
slides  have  occurred,  and  the  slopes  are  covered  with  grass  and 
bushes.    One  exposure  gave  the  following  section: 


Geology  0/ Long  Island. 


Drift, 


-   3  feet 
8  " 


Fiue  yellow  Band,  - 
M  icaceous  clay, 
Micaceous  sand. 


-    1  " 

25  " 


Total, 


:37  feet. 


The  micaceous  sand  occurs  at  the  foot  of  the  bluffs  along  the 
shore  in  this  vicinity.  It  may  also  be  seen  half  a  mile  west  of 
Orient,  in  a  bank  by  the  road-side. 

On  Gardiner's  Island  a  very  complete  section  is  exposed  on  the 
southeast  shore,  which  exhibits  the  strata  to  the  depth  of  about 
250  feet  (see  figs.  4&  5).  Here  stratified  sands  and  clays  of  vari- 
ous kinds  and  colors  are  raised  up  in  t  wo  parallel  anticlinal  folds. 
In  the  southerly  fold,  the  stratum  is  a  light  red,  fine,  plastic  clay, 
very  similar  to  that  at  Grossman's  in  Huntington  ;  it  is  here  ex- 
posed to  a  depth  of  about  100  feet  and  is  upheaved  at  a  high 
angle,  its  outer  slopes  dipping  about  45°,  while  along  the  axis  of 
the  fold  the  laminae  are  vertical.  The  northern  anticlinal  has 
about  15°  dip  on  either  side,  and  in  its  north  slope  is  a  stratum 
of  yellowish  clayey  sand  containing  a  bed  of  post-pliocene  shells, 
at  an  average  hight  of  15  feet  above  the  sea.  The  formation 
which  is  here  brought  to  view  probably  underlies  the  whole  of 
the  island,  as  it  is  exposed  at  various  other  points.  On  the  north 
and  southeast  shores  the  beds  are  very  much  disturbed  and 
folded,  and  the  surface  of  the  island  is  raised  in  a  series  of  par- 
allel ridges  corresponding  in  position  to  the  folds  and  having  a 
general  trend  of  N.  65°  E.  The  highest  point  on  the  island  is 
128  feet  above  the  sea ;  the  bluffs  along  the  shore  being  from  25 
to  70  feet  high.  The  fossiliferous  stratum  is  about  20  feet  hmg 
and  4  feet  thick,  containing  an  abundance  of  shells,  most  of 
which  appear  to  have  been  crushed  by  superincumbent  pressure. 
The  locality  was  visited  in  18G3  by  Prof.  Sanderson  Smith,  who 
describes  the  bed  as  150  to  200  feet  long.  Prof.  Smith  has  iden- 
tified the  following  species*  all  of  which  are  recent  :  ^Yassa 
trivittata,  N.  vibex,  Fusus  decemcostatus,  Purpura  lapillus. 
Coin  nib  ell  a  lunula,  ^Natica  duplicata,  JY.  heros,  Ghemnitzia 


*  Annals  N.  Y.  Lyceum  of  Nat.  Hist..  Vol.  VIII,  18G5. 
f  Species  also  collected  by  the  writer. 


Geology  of  Long  Island. 


355 


interrupta,  Crepidula  fornicata,  *C.  plana,  Tornatella  puncto- 
striata,  Bulla  canaliculata,  *  Venus  mercenaria,  *  OstreaVirgini- 
ana,  Pecten  Islandicus,  P.  Magellanicus,  Area  transversa,  A. 
pexata,  Cardita  borealis,  *Astarte  sulcata  or  undata,  Mactra  la- 
teralis, La cin a  radula,  *Mya  arenaria  ;  fragments  of  a  Bala- 
aas  ;  a  coral,  Astrangia  Dame. 

Napeagne  Beach,  east  of  Amagansett,  is  three  miles  long  and 
one  quarter  of  a  mile  broad,  consisting  entirely  of  white  quartz 
sand.  Along  the  shore  on  the  north  and  south  are  dunes  of 
drifted  sand  20  or  30  feet  high,  but  the  main  portion  of  the 
beach  probably  averages  less  than  10  feet  above  the  sea.  East 
of  the  beach,  the  country  for  twelve  miles  to  the  end  of  Montauk 
Point,  is  chiefly  a  terminal  moraine,  and  as  such  I  have  already 
briefly  described  it. 

Historical  Geology. 

Having  thus  reviewed  in  detail  the  various  strata  underlying 
the  drift,  we  come  now  to  consider  their  age  and  history.  AVith- 
out  attempting  to  decide  the  geological  equivalence  of  the  crys- 
talline rocks  at  Astoria,  we  will  discuss  the  unsolidified  deposits 
which  have  just  been  described. 

From  the  posiiion  and  strike  of  the  Cretaceous  strata  in  New 
Jersey  and  Staten  Island,  it  has  been  surmised  by  geologists  that 
they  underlie  Long  Island  throughout  the  whole  or  a  portion  of 
its  extent.  The  locality  at  which  the  strata  most  resemble 
the  Cretaceous  beds  of  New  Jersey  is  Glen  Cove,  where  the 
clays  already  described  are  probably  of  this  age.  If  the  Cre- 
taceous formation  extends  under  the  whole  of  Long  Island  it 
must  occur  at  a  very  great  depth,  since  deep  sections  at  points 
east  of  Glen  Cove  do  not  reveal  its  presence. 

In  regard  to  this  formation  and  the  following,  it  should  be  un- 
derstood that  sufficient  data  have  not  yet  been  obtained  to  war- 
rant an  attempt  to  map  out  their  extent.  The  only  exposures 
are  in  vertical  sections  along  the  shore  and  in  various  clay-pits 
or  similar  excavations  ;  and  there  being  an  immense  amount  of 
quaternary  material  overlying  them,  no  satisfactory  degree  of 
accuracy  can  be  as  yet  attained  in  this  regard. 


*  Species  also  collected  by  the  writer. 


Geology  of  Long  Island. 


The  Tertiary  strata  of  Long  Island  cannot  as  yet  be  identified 
with  m iuli  more  certainty  than  the  Cretaceous.  From  their 
character  and  position  we  may  surmise  that  the  brown  and 
red  plastic  clays  of  Huntington,  Gardiner's  Island  and  else- 
where, belong  to  the  age  in  question,  but  we  have  no  palaeon- 
tological  evidence  except  from  the  shark's  tooth  found  on  Lit- 
tle Neck,  which  would  identify  the  bed  in  which  it  occurred 
as  Eocene  or  Miocene.  The  stratified  sands  and  gravels  however, 
which  overlie  the  supposed  Cretaceous  and  Tertiary  beds,  and  in 
turn  are  overlain  unconformably  by  surface  drift  and  till,  we 
may  accept  as  Post-pliocene,  from  the  analogy  of  their  composi- 
tion, structure  and  position  to  the  deposits  of  Gardiner's  Island 
and  Sankaty  Head,  of  which  the  fossils  determine  the  age  beyond 
question  ;  unfortunately,  however,  there  is  no  unconforrnability, 
to  show  where  the  Tertiary  ends  and  the  Quaternary  begins. 

At  various  times  and  places,  fossil  shells  and  lignite  have  been 
found  on  Long  Island.  J  append  a  synopsis  of  a  list  of  these 
compiled  by  Elias  Lewis,  Jr.,  from  Mather's  Report  and  from 
other  sources  : 


Geology  of  Long  Island. 


357 


Mature  of 
Fossil. 


Locality  and  Date. 


Recent  shells.     Ft.  Lafayette. 
Pvrula,  clam,     New  Utrecht, 
oyster. 

Clam  and  oyster  Well  in  Prospect  Park, 
shells. 

Clam  and  oyster  Well  at  Flatbush  Alms 

shells.  house. 
2  Petrified  clams  Flatbush. 


Depth. 


-53  ft. 
-67  ft. 


40—50  feet, 


100  ft. 


flxogyra  costata,  Bet,  Brooklyn  and  Flat-  60  ft. 
'    withgr'n  s'nd.  j  lands. 

Oyster  shells.      Hio:h  grounds  in  Brook-  73  ft. 

>  I  lyn. 

Clamshells.  Fort  Greene,  1814.         70  ft. 

\Anomiaephip-  Cor.  Jay  &  Front  Street,  15  ft. 

j    pium.  Brooklyn. 

Oyster  shells.  .    Nassau  Gas  Light  Co.,  127ft.  6  in 

Williamsburg. 

Log  of  wood.  Bus'hwick.                    40  ft. 

Shells.  jNewtown.                    70  ft, 

Clam  shells.  East  New  York.            80  ft, 

Wood.  3  miles  W.  of  Jamaica.  25  ft. 


Authority. 


E.  Lewis,  Jr. 
Thompson's  Hist. 

of  L.  I. 
E.  Lewis,  Jr. 


W.  J.  Furman  An- 
tiquities of  L.  1. 
Dr.  J.  C.  Jay, 
Ann.  of  Lyc. 
Nat,  Hist.,  1842. 
|Furman's  Antiqui- 
I  ties. 

E.  Lewis,  Jr. 


Thompson's  Hist. 


Clam  and  oyster  Lakeville. 
I  shells. 


C 1  a m .  oy st er  and  La ke vil  1  e . 
i    scallop  shells.' 


85ft.  above^ 

tide  140  HenryOnderdonk. 
tol60tf.  Jr. 


2d. 
21. 
22. 
2:!. 
U 
25. 
26. 
27. 
28. 

29. 
30. 
81. 
32. 

33. 


34. 


Wood. 

Oyster  shells. 
Shells. 

Stem  of  Crinoid. 
Lignite. 
Wood. 
Wood. 

Carb'nized  wood 
Lignite. 
Lignite. 
Wood. 

CareJiarodon  an- 

gustidens. 
Log  of  wood. 
Clam  shells. 
Shells. 

Bones  of  Masto- 
don. 
Venus  mercenaria 


Great  Neck,  1813. 
Manhasset,  1813. 
Bet.  Manhasset  and  Ros- 
lyn. 

Barnum's  Island. 

Near  Westbury. 
Hempstead  Plains,  1804. 
Sea  Cliff.  1845. 
Glen  Cove,  1834. 
Jericho,  1878. 
Cold  Spring. 
Little  Neck. 

Strong's  Neck. 
Shelter  Island,  1898. 
Wells  at  Amagansett. 
Jamaica  Pond,  1846. 


200  feet 
above  tide. 
47  ft. 

50  ft. 
78  ft. 
140  ft. 

168  ft. 
100-383  ft. 
Great  d'pths 
100-108  ft. 
94  ft. 
40  ft. 
96  ft. 
110  ft. 


40  ft. 
57  ft. 


J.  H. 
dieu. 


L'Homme 


Yaphank. 


Osh 


vjiniana  S-dg  Harbor,  1864. 


(    100  feet 
■  -  above  tide. 
(  20  ft. 

180  ft.  above 
;  tide. 


Thompson's  Hist, 


E.  Lewis,  Jr. 

Thompson's  Hist. 
D wight's  Travels. 
Isaac  Coles. 
E.  Lewis,  Jr. 

Thompson's  Hist. 
P.  B.  Sills. 

Thompson's  Hist. 

E.  Lewis,  Jr. 


E.  Lewis,  Jr. 


Dr.  Cook. 


Geology  of  Long  Island. 


In  view  of  the  fact  that  we  have  nowhere  else  any  good  evidence 
of  a  change  of  sea  level  amounting  to  200  feet  in  t  lie  vicinity  of  New 
York  during  the  Glacial  epoch,  we  can  only  account  for  the  high 
elevation  of  some  of  these  fossils  by  supposing  that  they,  with 
their  containing  beds,  have  been  raised  to  their  present  position 
by  glacial  action  in  the  manner  I  shall  describe. 

Of  the  physical  conditions  under  which  the  presumed  Creta- 
ceous and  Tertiary  beds  were  deposited,  we  know  nothing; 
though  it  is  reasonable  to  conclude  that  they  consist  of  the  debris 
of  New  York  and  New  England  rocks  carried  down  from  the 
highlands  and  deposited  along  the  coast  by  rivers  or  by  other 
agencies  of  transportation.  The  overlying  deposits  of  strati- 
lied  gravel,  sand  and  clay,  part  of  which,  as  before  stated,  arc 
equivalent  to  the  "yellow  drift"  of  New  Jersey,  are  also  difficult 
to  account  for.  They  consist  largely  of  transported  material 
from  older  beds,  and  by  their  structure  indicate  that  they  have 
been  formed  by  swift  currents  which  carried  along  and  deposited 
coarse  and  fine  material  mingled  together.  Their  fossils,  so  far 
as  we  know,  exclude  them  from  the  Tertiary,  and  they  underlie 
the  drift  unconformably,  although  by  definition  the  Glacial  pe- 
riod begins  the  Quaternary  age. 

If,  however,  we  assume  in  the  Quaternary  a  succession  of 
glacial  epochs,  or  alternate  periods  of  advance  and  retreat  of 
the  ice-sheet,  as  suggested  by  Croll's  theory,  we  can  explain 
the  origin  of  the  beds  in  question  by  supposing  that  during 
the  epoch  of  glaciation  immediately  preceding  their  deposi- 
tion, the  ice-sheet  did  not  reach  so  far  south,  while  the  floods  of 
of  the  succeeding  warmer  epoch  modified  and  spread  over  the 
sea-bottom  the  drift  thus  formed. 

In  order  to  appreciate  more  exactly  the  relations  of  these  Post- 
pliocene  beds  to  the  glacial  drift,  it  will  be  necessary  to  consider 
some  very  interesting  phenomena.  Along  the  north  shore  of 
Long  Island  from  Flushing  to  Orient  Point,  are  exhibited  most 
striking  evidences  of  glacial  action.  We  find  the  stratified  era- 
vels,  sands  and  clays  upheaved  by  the  lateral  pressure  of  the  ice- 
sheet  and  thrown  into  a  series  of  marked  folds  at  right  angles 
to  the  line  of  glacial  advance,  which,  judging  from  the  grooves 
and  striae  on  the  rocks  of  New  Yrork  and  Connecticut,  was  about 
S.  30°  E.    The  glacier  having  thus  crumpled  and  folded  the  un- 


Geology  of  Long  Island. 


359 


derlying  strata,  it  evidently  rode  over  them  and  continued  its 
course  southward,  pushing  before  it  an  immense  mass  of  sand 
and  gravel,  together  with  debris  from  the  rocks  of  New  York  and 
New  England. 

The  theory  that  Long  Island  Sound  was  a  body  of  water  pre- 
vious to  the  arrival  of  the  ice-sheet,  would  seem  to  be  sustained 
by  the  character  of  the  detritus  deposited  by  the  ice  on  Long- 
Island.  From  Brooklyn  to  Whitestone,  where  the  sound  is  nar- 
row, the  till  or  drift  proper  is  quite  conspicuous  ;  east  of  this  it 
becomes  less  noticeable,  and  beyond  Eo^lyn,  as  before  stated,  it 
does  not  again  occur  in  abundance  until  we  reach  the  vicinity  of 
Greenport,  where  the  Sound  again  grows  narrow.  This  seems 
to  be  due  to  tl^e  fact  that  the  finer  debris  of  the  northern  rocks 
was  carried  along  imbedded  in  the  lower  part  of  the  glacier. 
The  channel  of  the  East  Eiver,  owing  to  its  narrowness,  was 
filled  up  and  passed  over,  the  till  being  deposited  to  form  the 
range  of  hills  near  Brooklyn  ;  but  in  crossing  the  broader  part 
of  the  Sound,  the  ice  probably  lost  the  greater  portion  of  its  load 
of  till,  and  only  carried  over  the  boulders  which  were  on  the  sur- 
face or  in  the  upper  part  of  the  glacier.  On  reaching  the  north 
shore  of  the  island  the  alluvial  gravel  and  sands  were  scooped  up 
and  pushed  forward  in  front  of  the  ice-sheet,  to  form  the  "  mo- 
raine," and  the  boulders,  when  the  ice  melted,  were  deposited 
on  the  surface.  The  map  shows  that  the  principal  bays  on  the 
north  shore  penetrate  the  land  in  a  direction  identical  with  that 
of  the  advance  of  the  glacier.  We  may  reasonably  infer  from 
this  fact,  that  these  indentations  were  ploughed  out  by  project- 
ing spurs  of  ice,  and  the  inference  is  supported  by  the  fact  that 
the  bays  are  walled  in  by  high  ridges  which  have  been  formed 
largely  through  the  upheaval  of  the  beds  by  lateral  thrust.  The 
best  example  of  this  displacement  in  the  formation  of  a  bay  is 
shown  in  the  section  at  Grossman's  clay-pit  in  Huntington,  (Fig. 
2)  which  I  have  previously  described.  Harbor  Hill,  which  stands 
at  the  head  of  Hempstead  Harbor,  is  384  feet  high,  and  chiefly 
consists  of  gravel  and  sand  more  or  less  stratified.  Jane's 
Hill,  four  miles  S.S.E.  of  the  head  of  Cold  Spring  Harbor,  is 
883  feet  high,  and  is  composed  of  the  same  materials.  In  the 
vicinity  of  each  of  these  hills,  moreover,  there  are  other  ridges 
and  elevations  averaging  about  300  feet  in  height.  Southeasterly 


360 


Geology  of  Long  I  si  a  nil. 


from  Huntington  Bay  we  have  the  Dix  Hills  and  Comae  Hills 
rising  about  250  feet.  Southeast  of  Smith  town  Harbor,  we  have 
Mi.  Pleasant,  200  feet  in  height  ;  in  a  like  direction  from  Stony 
Brook  Harbor,  are  the  Bald  Hilly,  also  200  feet  high.  Again 
we  have  Beulands  Hill,  which  is  340  feet  m  height,  and  has  the 
seme  general  bearing  from  Port  Jefferson  Harbor.  About  South 
30°  East  from  Wading  River,  where  there  is  quite  a  deep  valley, 
we  rind  Terry's  Hill,  175  feet  high.  South  of  Great  Peconic 
Bay  rise  the  Shinnecock  Hills,  140  feet,  and  southeasterly  from 
Little  Peconic  Bay  are  the  Pine  Hills  about  200  feet  high.  Prom 
these  instances  it  will  be  seen  that  the  areas  of  high  elevation 
bear  a  very  marked  geographical  relation  to  the  deep  indentations 
of  the  coast.  That  this  relation  is  due  to  glaciaJ  action,  seems 
more  than  probable,  as  it  can  scarcely  be  an  accidental  coinci- 
dence that  the  highest  hills  on  the  island  should  be  in  a  line  with 
the  deepest  bays  on  the  northern  coast,  and  that  the  course  of 
these  bays  should  coincide  with  that  of  the  glacier. 

At  every  point  along  the  north  shore  where  a  section  of  the 
strata  is  exposed,  the  flexed  structure  of  the  beds  under  the  drift 
may  be  observed.  On  Gardiner's  Island,  these  folds  are  remark- 
ably prominent,  the  surface  of  the  island  being  broken  with  nu- 
merous parallel  ridges  having  a  general  trend  N.  G5°  E.  These 
ridges  correspond  to  folds  in  the  stratified  beds,  which  the  sur- 
face drift  overlies  unconformably.  and  as  they  are  at  right  angles 
to  the  line  of  glacial  advance  it  is  difficult  to  conceive  any  agency 
which  could  have  produced  them  except  the  lateral  thrust  of  the 
ice-sheet,  Unless  these  phenomena  can  be  referred  satisfactorily 
to  some  other  cause,  and  of  this  I  very  much  doubt  the  possi- 
bility, we  have  in  these  folds  a  strong  argument  against  the  ice- 
berg theory,  as  it  seems  evident  that  a  mere  drifting  berg  could 
not  develop  sufficient  progressive  force  to  do  the  work  here 
shown.  A  similar  origin  may  be  attributed  to  the  ranges  of 
hills  which  form  the  so-called  "back-bone"  of  the  island;  as 
t  heir  structure  indicates  that  they  have  been  formed  partly  of 
gravel  and  sand  transported  from  the  north  shore,  and  partly 
through  the  upheaval  of  the  stratified  beds  by  the  friction  of  the 
moving  mass  of  ice.  As  the  downward  pressure  of  the  glacier  was 
about  450  lbs.  per  square  inch  for  1,000  feet  of  thickness,  and  its 
progressive  force  was  only  limited  by  the  resistance  of  the  ice,  it 


Geology  of  Long  Island. 


361 


is  quite  reasonable  to  assume  it  capable  of  producing  such  a  re- 
sult. At  one  locality,  West  Deer  Park,  this  is  manifestly  the 
case,  and  I  have  no  doubt  that  in  time  it  will  be  found  generally 
true.  The  numerous  springs  that  issue  from  the  hillsides  along 
the  north  shore  also  lead  one  to  infer  that  the  substratum  of  clay 
has  been  raised  up  in  the  centre  of  the  hills.  The  occurrence  of 
the  springs  might  be  accounted  for  hypothetical^  by  supposing 
that  these  hills  are  the  remnants  of  unequally  eroded  horizontal 
strata  of  sand  underlaid  by  clay  ;  but  this  we  know  is  not  the 
case. 

Mr.  Upham,  in  his  discussion  of  the  moraines,  attributes  all 
the  stratified  deposits  to  diluvial  and  alluvial  action  in  the  Cham- 
plain  period,  to  which  the  Gardiner's  Island  deposit  has  been 
erroneously  referred.  He  also  concludes  that  the  more  southern 
drift  hills,  which  are  from  200  to  250  feet  high,  were  formed 
in  ice-walled  river-channels  formed  upon  the  surface  of  the  gla- 
cial sheet  when  rapidly  melting.  That  this  process  has  taken 
place  in  some  cases,  is  quite  probable,  as  there  are  undisputed 
kames  in  certain  places,  but  from  the  analogy  of  the  deposits  in 
question  to  the  others  described,  I  am  inclined  to  refer  them 
generally  to  the  same  causes. 

The  changes  which  have  occurred  on  Long  Island  since  the 
retreat  of  the  glacier,  have  been  mainly  topographical,  and  un- 
questionably very  extensive.  The  streams  of  the  Champlain 
epoch  carried  down  the  drift  from  the  morainal  hills  and  distri- 
buted it  on  the  plain  to  the  south,  forming  in  many  places  local 
beds  of  clay.  In  the  vicinity  of  Bethpage  and  elsewhere,  are 
hillocks  of  stratified  sand  similar  in  appearance  to  the  New  Eng- 
land kames.  The  valleys  mentioned  above,  which  have  been  ex- 
amined by  Elias  Lewis,  Jr.,  are  unquestionably  the  channels  of 
streams  resulting  from  the  melting  of  the  glacier. 

The  coast  line  of  the  island  is  rapidly  changing,  on  account  of 
the  action  of  the  swift  westerly  cm-rents  which  are  wearing  away 
the  east  end  and  depositing  the  sediment  along  the  north  and 
and  south  shores.  By  this  means  the  bays  which  open  into  the 
Sound  are  rapidly  becoming  shallow.  The  Great  South  Beach 
is  also  an  evidence  of  the  action  of  the  waves  and  currents  in 
changing  the  outline  of  Long  Island.  We  have  moreover  abund- 
ant evidence  that  the  south  shore  has  been  gradually  sinking. 


Geology  of  Long  Island. 


This  subsidence  probably  began  in  the  later  Quaternary  and  may 
be  still  continuing. 

Economic  Geology. 

Magnetite  :  this  is  the  only  metallic  ore  found  on  Long  Island, 
and  occurs  almost  everywhere  on  the  benches  in  the  form  of  sand. 
It  is  not,  however,  sufficiently  abundant  in  any  one  locality  to 
render  its  collection  profitable.  A  company  was  started  some 
time  since  for  the  purpose  of  separating  the  ore,  in  the  vicinity 
of  Quogue,  from  its  associated  quartz  and  garnet  sand  by  means 
of  powerful  electro-magnets,  but  the  enterprise  proved  unsuc- 
cessful. 

Iron  Pyrites  in  its  white  variety,  or  marcasite,  is  common  in 
the  lower  clay-beds,  but  does  not  occur  in  sufficient  abundance 
to  pay  for  utilizing  it. 

Lignite  occurs  only  in  small  quantities  and  usually  at  great 
depths. 

Peat  of  an  inferior  kind,  composed  of  the  matted  roots  of 
grasses  and  other  plants,  occurs  at  the  heads  of  most  of  the  bays 
on  the  south  shore,  but  is  not  used  to  any  extent. 

Although  not  productive  of  any  of  the  valuable  minerals,  Long 
Island  may  be  considered  peculiarly  rich,  from  the  fact  that 
almost  the  whole  of  the  island  can  be  utilized  in  the  arts  and 
trades.  Its  sands  and  gravels  are  of  every  kind  in  use,  and  its 
clays  are  suited  for  the  manufacture  of  fine  grades  of  brick 
and  pottery.  The  former  materials  are  largely  shipped  from 
Port  Washington  and  the  vicinity,  for  building  purposes. 

The  most  extensive  deposit  of  fine  pottery  clay  occurs  at  Glen 
Cove,  on  the  premises  of  the  Messrs.  Carpenter.  This  clay  is 
very  plastic  and  burns  a  light  cream-color.  The  friable  quartz 
pebbles  described  above,  produce  when  ground  the  finest  quality 
of  white  sand  for  glass  and  pottery.  The  deposit  of  kaolin  is 
also  unsurpassed.  In  addition  to  these  materials,  this  locality 
furnishes  fire-sand  for  pottery,  grey  and  blue  pottery  clays,  and 
an  excellent  fire-clay. 

The  next  locality  of  note  is  Huntington.  In  this  town  is  an 
immense  deposit  of  the  finest  brick-clay,  upheaved  to  such  an 
elevation  that  it  is  easily  accessible.    The  beds  are  worked  at 


Geology  of  Long  Island. 


363 


Grossman's  and  Jones's  brick-yards,  and  extend  throughout 
Lloyds'  Neck.  Between  Huntington  and  Cold  Spring  a  large 
deposit  of  white  pottery-clay  has  been  worked  for  many  years. 
The  brick-clay  extends  east  over  ten  miles,  and  is  worked  at 
Eckerson's  yard  on  East  Neck,  and  Provost's  at  Fresh  Ponds. 
At  Eckerson's  and  at  Sammis's  pits  on  Little  Neck,  are  immense 
deposits  of  fire-sand  which  extend  over  Eaton's  and  Lloyd's  Necks. 

A  little  west  of  Greenport  are  two  brick-yards  at  which  a  bed 
of  glacial  clay  is  being  worked.  Between  these  two  yards  is  a  bed 
of  mottled  blue  clay  used  for  making  flower  pots.  The  most  ex- 
tensive deposit  of  all,  however,  is  that  on  Gardiner's  Island.  This 
clay  is  unsurpassed  for  the  manufacture  of  bricks,  and  from  the 
abundant  supply  of  moulding-sand  and  the  easy  accessibility  of 
the  locality  by  water,  must  in  time  prove  an  important  source 
of  revenue. 


DESCRIPTION  OF  PLATE  XXVII. 
Fig.  1.    Scale  1  ixcn=60  feet. 
Section  at  Carpenter's  clay-pits,  Glen  Cove,  looking  east. 

a.  Glacial  drift. 

b.  Yellow  sand. 

c.  Friable  quartz  gravel  and  sand. 

d.  Fire-clay. 

Fig.  2.    Scale  1  incii=60  feet. 
Section  at  Crossman's  brick-yard,  Huntington,  looking  north. 

a.  Glacial  drift. 

b.  Quartz  gravel,  stratified. 

c.  Sandy  clay  or  "  loam," — upper  half  yellow,  lower  half  blue. 
(1.  Diatomaceous  earth  mixed  with  clay. 

e.  Yellow  sand,  stratified. 
/'.  Tied  laminated  clay. 

g.  Brown  laminated  clay. 

Fig.  3.    Scale  1  inch=30  feet. 
Section  at  Fulmer's  brick-yard,  Greenport,  looking  north. 

a.  a.  Reddish  glacial  clay,  with  fragments  of  mica  schist. 

b.  Red  clay. 

c.  Micaceous  sand,  laminated. 


364 


Geology,  of  Long  Island. 


Figs.  4  &  5.    Scale  1  inch=00  feet. 

Section  on  southeast  shore  of  Gardiner's  Island,  looking  west. 

a.  Glacial  drift. 

b.  Laminated  white  sand. 


c.  "      white  sand  streaked  with  limonite. 

d.  "      yellow  and  blue  clayey  sand. 

e.  "      white  and  yellow  sand. 
/.  "      grey  and  yellow  sand. 

{j.  "      yellow  sand  with  blue  clay. 

h.  "      gre}^  sand  with  red  clay. 

i.  "      red  clay  and  grey  sand. 
j.          "      grey  sand  with  red  clay. 

h.  "  sand,  top  streaked  with  limonite. 
I.  Dark  greenish  clay. 

V  "  "       "    somewhat  granular. 

m.  "     grey  clay  and  sand,  laminated. 


m'  Beach  sand  streaked  with  limonite. 

ii.  Laminated  sand,  stratification  obscured  by  a  slide  and  possibly  in- 
terrupted by  a  fault, 
o.  Laminated  greenish  sand. 
p.  "      white  and  yellow  sand. 

r.  "      green  and  yellow  clayey  sand. 

s.  "      reddish  clayey  sand  with  fossil  shells. 

t.  Dark  greenish  clay. 
u.  Fine  laminated  sand. 


PLATE  XXVIII. 

Map  of  Long  Island,  showing  the  southern  limit  of  glacier  action.  (Pre- 
pared on  the  basis  of  the  U.  S.  Coast  Survey  Map.) 


Anna i.-.  Vol.  III.  No.  11.  Plate  XXVII. 


